I prefer to buy bitcoin than ethereum in this dip because bitcoin is promising to increase later and bitcoin is the main investment.
If I have many funds available, I will buy both bitcoin and ethereum but if it is not, I will buy bitcoin.
That will depend on how much funds you have to determine which coin you should buy but it is okay if you buy both bitcoin and ethereum even if you have limited funds.
I hope you do not confuse to decide but before you buy bitcoin or ethereum, make sure you analyze both so there will be no regret in the future.